1. Field of the Invention
This invention relates to sterilizers and, more particularly, to the automatic operation of a steam sterilizer.
2. Description of the Prior Art
Sterilization criteria for steam sterilizers are conventionally defined by subjecting items to be sterilized to a high quality steam (such as saturated steam) at a given temperature for a predetermined period of time. The items are placed in a sealed chamber which is then filled with saturated steam. Unfortunately, when the items are placed inside the chamber, air also enters the chamber. It has long been recognized that the removal of this air is one of the most critical portions of a sterilizing process, since the presence of air in the chamber prevents proper sterilization conditions, i.e., saturated steam at a given temperature, from being accurately monitored inside the chamber. Thus, it is important to remove air from the chamber in order to develop and accurately monitor the saturated steam conditions inside the chamber and, once developed, to accurately maintain these conditions throughout the duration of the sterilization time period.
It is known that the pressure and temperature variables of saturated steam are dependent variables when saturated steam is enclosed in a sealed chamber. However, this dependency is destroyed if the saturated steam condition is not completely maintained throughout the chamber.
In a known sterilizer of the type which generates steam inside of the chamber, the user/operator must visually inspect the pressure and temperature displays and then manually start a sterilization timer when the proper conditions are attained. However, once the timer is started, if either of the pressure or temperature variables change beyond the limits defining the required conditions for the sterilizing steam, the manually controlled timer continues to operate and it is possible that the items will not be properly sterilized at the end of the timed period.
It is desirable to develop apparatus which would automatically control the generation of steam inside the sterilization chamber so as to insure proper sterilization conditions at both the start and during the sterilization cycle.